About 198.18.0.0/15 segment

Solution 1:

According to RFC 6815, this subnet is used for benchmarking inter-network communications. I would not recommend using this as a private network space.

Solution 2:

Regarding the special purpose to that net, RFC 6815 is titled RFC 2544: Use on Production Networks Considered Harmful as a warning about such traffic generation until loss test procedures. Some in the ITEF argue so strongly about the need to air gap such a test procedure they added a dedicated private address space, and wrote a statement.

That is not the kind of network I would want to steal addresses from. Not in real networks outside the test lab. Low probability some network gear's RFC2544 test suite takes those addresses and makes something fall over, but potentially high impact.

For as much pristine, never before used address space as you need, implement IPv6.